It is usual, in particular in the automobile industry, to use snap couplers for the rapid connection of a fluid (for example fuel, oil or water) circuit element to another circuit element and for disconnection therefrom. In a substantially standardized manner, the industry uses male end-fittings having a cylindrical barrel surrounded by a flange, and the female couplers have a stepped cylindrical cavity, for housing at least the end of the barrel, and a resilient lock for locking the rear of the flange once the latter is in place. O-ring seals ensure sealing.
In most commercial couplers, the body of the coupler, generally made of molded thermoplastic, the lock, more often than not also made of a molded thermoplastic or possibly a metal, and the seals, generally made of an elastomer, consist of separate parts that are assembled, which makes the manufacture more complicated and increases the cost. This is the case, for example, with the coupler known from document FR 2 753 774 A, the lock of which is formed from a substantially undeformable ring that can slide radially between an off-center locking position and a centered protraction position, spring means allowing the ring to be returned from the retracted position to its off-center position. This is also the case with the coupler known from document EP 0 605 801 A, the lock of which is formed from a separate, elastically deformable piece of oval or diamond shape, certain parts of which lie, in the rest state, behind the flange,and can, when pressure is exerted on them, move away radially so as to let the flange pass. In such devices, if the sealing system consisting of one or two elastomer seals is included, there is a total of 5 to 7 pieces that must be assembled on an automatic machine in order to form the coupler. To partly solve this problem, in an alternative form of the latter device that has been commercialized, the separate part of oval shape is molded in one piece with the body, said piece being connected by two arms to the rear of said body. A rather similar device is shown in patents EP 0 530 485 and DE3 933 590. The plastic chosen for producing the piece is necessarily quite a rigid plastic with light elasticity, such as nylon-6,6. Such arrangements prove to be quite fragile, and the deformation of the oval is not easy to control and there is a risk of causing permanent set, or even destruction, of the linking arms.
Document EP 0 982 525 in the name of the Applicant discloses a female snap coupler for cooperating with a male fastening end-fitting of the type with a central barrel and a flange, the coupler comprising, on the one hand, a body made of a rigid plastic and having a tubular part with raised features for connecting to a pipe and a part forming a stepped cylindrical cavity for housing at least the end of the barrel and, on the other hand, at the front of the body, a lock, also made of a rigid material, intended for locking the flange once the latter is in place, the lock and the body being fastened together by at least one flexible piece overmolded using dual-injection molding, at least one annular seal ensuring that it sealed. The lock is made in the form of a ring with radial movement, supported by linking arms.